Historically, there has been a long felt need in the floor covering arts for a material which could be applied directly to a concrete slab having a high hydrostatic pressure such as frequently encountered below grade. Linoleum, the first nontextile resilient floor covering, developed about 1860, was limited to use on suspended floors because of poor moisture resistance characteristics.
In the early 1920's, asphalt tile was introduced to the marketplace which had improved moisture resistance characteristics over linoleum but nevertheless failed under relatively high hydrostatic pressures commonly found in below-grade concrete slabs. The asphalt tile was sufficiently water penetration resistant that the only avenue of escape for water in wet areas was by seepage or evaporation through the seams between tiles. Ground water saturating the concrete slab in wet areas contained a variety of dissolved salts including alkaline salts leached from the concrete. Evaporation left unsightly salt deposits along the seams and, in time, raised the tiles along the seams. Additionally, because of the non-porous character of asphalt tile, water tended to collect along cracks or holes in the concrete forming a water blister beneath the tile which would be extruded to and upwardly through the seams to lay on the surface and cause delamination of the adhesive bond between the tile and the concrete. Vinyl asbestos and pure vinyl tiles suffered from the same disadvantages as asphalt tile.
In the early 1950's vinyl surfaced resilient floor having an organic felt backing was introduced. The organic felt was not water resistant suffering from dimensional changes due to swelling and fungi degradation. The organic felt backing was replaced with an inorganic asbestos backing in the late 1950's but moisture problems remained including dimensional instability resulting in shrinkage with resultant seam opening and water evaporation through the seams leaving a salt residue.
In the early 1960's cushion vinyl floor covering was introduced having an inorganic, asbestos felt backing, a body layer of vinyl foam and a top, wear layer of vinyl. Nevertheless, such cushion vinyl flooring failed under high moisture conditions.
The asbestos backing in cushion vinyl flooring is porous and therefore adsorbed large quantities of moisture. The vinyl foam body had an open cellular character and is thus also moisture permeable. However, the wear layer is non-porous and hence moisture impervious. As a result, both water and dissolved salts accumulate in the layers beneath the wear layer.
Commonly, a pattern is imprinted with color dyes on top of the intermediate body layer. The dissolved salts, particularly alkaline salts leached from the concrete slab degradated many of the dyes in a relatively short period of time resulting in unsightly, spotty color changes. Additionally, plasticizers employed in the foam layer encouraged the growth of unsightly black fungi in the foam layer and intermediate it and the wear layer. Neither condition can be remedied by other than removal and replacement of the floor covering.
At present, the only available method to prevent these problems is the use of a waterproof membrane beneath the concrete slab which is costly, difficult to properly install and difficult to maintain waterproof. As a result, many contractors either do not install such a membrane or install it improperly with the result that the flooring deteriorates. In warm, moist climates, this deterioration can occur in a matter of weeks to a few months.
It is therefore among the objects and advantages of the present invention to provide a laminate suitable for floor covering on concrete under extremely high hydrostatic conditions which will permit the spread of moisture from extremely wet areas without the development of water blisters yet will not yield to color degradation of dyes on top of a foamed, cushion layer or to the growth of fungi therein.
Another object of the present invention is to provide a laminate of the character aforesaid which is dimensionally stable, and resistant to attack from alkaline and other salts as well as fungi under extreme moisture conditions.
Still another object of the present invention is to provide a laminate as aforesaid which can be installed with seams between adjacent segments sealed against water evaporation by well-known techniques.
Yet a further object of the present invention is to provide a laminate as aforesaid which is suitable for use as a floor, wall or other covering such as upholstry and which can be employed on concrete slabs under extremely high moisture conditions without the use of waterproof membranes beneath the slab.
These objects and advantages as well as other objects and advantages may be achieved by the laminate disclosed herein.